Polyphenols, a diverse group of phytochemicals found abundantly in fruits, vegetables, tea, coffee, and wine, have become a subject of interest in bone health research. Several in vitro and animal studies indicate that polyphenols can positively affect the skeletal system by modulating bone metabolism, reducing oxidative stress, and influencing inflammatory pathways. For example, flavonoids such as quercetin and catechins have been shown to stimulate osteoblast activity (bone formation cells) and inhibit osteoclastogenesis (bone resorption cells), potentially helping to maintain or improve bone density. Antioxidant properties of polyphenols may further protect bone tissue from oxidative damage, which is implicated in osteoporosis and age-related bone loss.

Some epidemiological studies in humans suggest a correlation between higher polyphenol intake and greater bone mineral density or reduced fracture risk, though these are often observational and do not establish causality. Clinical trials are limited, but a few small-scale human studies (e.g., on green tea polyphenols) have reported modest improvements in bone turnover markers or bone mineral content.

However, while preclinical data and some epidemiological evidence are promising, robust, long-term randomized controlled trials in humans are lacking. Thus, there is moderate scientific evidence (rated 3/5) supporting the use of polyphenols for bone health, but more research is needed for conclusive recommendations.